Insulated wire



ICZZZA XR 2,305,325 Wal/0% Dec. 15, 1942. P. M. SNYDER 2,395,325

INSULATED WIRE Filed Aug. 23, 1941 .l INVENTOR im dww.' W. SWAN autres stares lerger ortica A INSULATED WIRE Purdum M.` Snyder, Een Avon, Pa., assignorto H. H. Robertson Company, Pittsburgh, Pa., a. g corporation of Pennsylvania Application August 23, 1941,3Serial No. 408,134

12 claims. (c1. 174-120) vThis invention relates to rubber covered intemperature at which saturation is conducted sulated Wire. approximates 350 E. in order to render the bitu- In general, the object of the invention is to minous impregnant or saturant sufficiently fluid produce a novel and improved rubber coated into thoroughly effect the desired saturation of the 'sulated wire which may be economically manu- 5, braid or vsimilar textile layer during the passage factored, possesses the general physical characof the wire through the bath at the relatively teristics as to flexibility, maintenance of its inhigh speed of from 100 to 400 feet per minute.-

sulating characteristics over long periods of time, In practice, it has been found that bituminous and other general characteristics comparable to materials are satisfactory having a hardness or the rubber covered insulated wire now upon the 1'.) penetration i from l l n 1 e at '77 vmarket, and which in addition possesses the lELusing lo() grams for 5 seconds, in accordancel ability to retard propagation of flame when t he with the standard methods of testing bituminous viteismsimigjectedztgmm ti'iegiuzeptwslgtigg gf o grg. materials for penetrationand hardness.

,./j'j'With this general object'in view, and such After the partially completed wire has been others as may hereinafter appear, the invention lo saturated and as it comes from the saturating consists inthe flame retarding rubber covered inbath, it is usually reeled up and stored to be subsulated Wire hereinafter described and particusequently nished, and in order to apply the n-l larly denned'in the claims at the end of thi ishing coat the wire is passed through a bath ofspecification. the finishing composition which preferably com- In the drawing, Fig. l illustrates a length of a prises a bitinous computi 1.. l u t.

rubber vcovered insulated wire embodying the ining login from I" u l. n n.. ing

vention, and Fig. 2 `is a cross-section on the line a n *rt n 'n Wei 2:-2 of Fig. l. In accordance with the usual from 3 to 18, and preferably wi 1n e ts process which has heretofore been employed in of Yfrom 6 to 10 when measured using 10) grams the production of rubber covered insulated wire, 25 for 5 seconds, as above described. It is preferred the 'copper wire H3 is preferably provided with that the finishing composition not be too hard 'atng of tin l2, and the rubber insulation i4 as otherwise a tendency to flake from the surface t maybe applied directly over the tin coating by i the wire is experienced, and if too soit, then 'an extrusion process, by being Wrapped about the wire-soon gets out of shape when reeled in a the "Wire, or in any other suitable manner. 3o coil, and `further will not satisfactorily pull Thereafter a cotton braid or similar textile co'vthrough the usual Wiring conduitsduri-ng the erin-g is wrapped or served over the rubber insu- N use oi the wire in Wiring buildings and the like. lation and the partially completed wire is then In order to assist the pulling of the wire through passed through an impregnating bath of a bithe conduits an additional lubricating coat in tuminous `material to weatherproof and saturate 35 the nature o a wax or parain coat, and also the textile covering It. After the wire has been vif desired, annderlying color coat, may be ap-Y thus saturated with the bituminous impregnant, plied to the iinishing coat of the rubber covered it may be immediately iinished, or in accordance insulated wire. with the usual practice, such wire is permitted In producing the presnt bitmious composito ccol .and in either instance is wiped to remove 4to tion possessing the desir '4f g ropthe surplus impregnant from the surface thereof ertiges, a bitin ir. as is utilized and a, d e and then passed through a bath of a bituminous proportion o slp is incorporated finishing composition to apply a' finishing coating therein. The biti'r'io ,s may comprise any 2i! thereto. In some instances it may be desirof the natural aspha ts, gilsonite, steam reduced able to color the finishing coating as indicated 45 and air blown asgha ts from petroleum residua, by a coloring layer '22 and also to provide a lucolft'rmimes and stear'tchewand brisant in the nature of a parain, wax, or simitu'iswtliew'he metallcsapmmay comprise lar surface coating 24. ams'tlected from the soafmrggi the group In accordance with the usual commercial pracof mung of magg affeseL iron zinc W und y ea-. 4 Ia-rtice the speed at which the insulated wire 1s 50 chromium, `cobalt, aluminum, magnesiumdgad passed thro-ugh the saturating bath varies from aldfb'riumfb't' beste'sis hai''ben secured 100 to 400 feet per minute so that the saturant utiliigmsap selected from the soaps from or impregnant is required to be a relatively low the group of metals consisting of iron, Zinc alui melting point bituminous material, varying in minumv and ,barium. Q r 1 es or moisfowsuay be li f melting point ,from lOJto 200 F. The usual 55*rrtill'2'in-an amount withinm'f from I 3 to 15% by weight of the bituminous composi- 'tlbmi'rdpff'e'ablyiom 6 to 15 0 o such soaps. The incorporation of`t ese metallic soaps is preferably accomplished by mixing the previously prepared soaps, substantially free from moist- 5 ure, with the bituminous composition at an elevated temperature, preferably above 150 F. or at such a temperature at which the bituminous base becomes sufficiently fluid to render the dispersion of the soap therein a simple mixing procedure. In some instances, incorporation of the soap may be caused to take place directly in the bituminous composition, such for example as by incorporating Zinc oxide in a bituminous composition having blended in it a fatty acid and heating the mixture until saponiiicaticn has been completed and the moisture resulting from the reaction has been dissipated. The quantity of zinc oxide added should be the amount required to satisfy the acid content and in such quantity that the total soap formed is within the prescribed limits of from 3 to 15%.

WhlW-nemmemm flame re ar ance o e bituminous compositions, nevertheless, 5ecause"'o' the fact that manganese appears to be such an active catalyst, it is preferred for many purposes to utilize a soap or mixtures of soaps selected from the group comprising the soaps of iron z in c, aluminum and barium, as such soaps appear to produce compounds efficient 3o in flame retardance and at thesame time of relatively permanent physical characteristics.

Ihe present bituminous compositions possess effective flame retardance particularly useful in the production of rubber insulated cotton covered wire commonly known as code wire. Rubber insulated cotton covered wire having iire resistance and moisture proof properties is so made by first saturating the cotton braid with a stearine pitchbearing composition, and then coating this saturated Wire with a stearine pitch-bearing compound. In addition to making such wire fire resisting and moisture resisting, these stearine pitch-bearing compounds must have such physical properties so as to impart' to the nished Wire the ability to comply with other performance requirements such as exibility, temperature stability and a low coeflicient of friction. Typical examples of these performance requirements follow in a description of a ame test and a moisture absorption test.

Flame test Support an 18" sample vertically and rigidly in a room from which all drafts are excluded. A flame indicator of gurnmed Kraft paper, M2 Wide and 5 mils thick, shall be Wrapped once around the sample with its lower edge l0 above the point at which the flame is applied. The ends of the indicator shall be pasted evenly together and shall G0 project 3A on the side of the wire opposite to that on which the flame is applied.

Apply the 11/2" blue cone of a 5" name (from a 1A Bunsen burner having 1A" inlet and to l mouth) at an angle of 20, approximately 3" 65 from the bottom of the sample, for 15 seconds, then remove for 15 seconds. This process is repeated four times, after which the sample shall not continue to burn for more than one minute and the paper indicator shall not be burned more than 25% of its area.

M oz'sture absorption test A sample shall be bent around a mandrel, the

diameter of which shall be determined from the overall diameter of the wire as follows:

The sample shall be immersed in distilled water at room temperature for '72 hours after which the braids shall not have absorbed more than 15% of their weight.

Stearine pitch is a by-product of the fatty acid industry and isaccordngly limited in supply. In addition, because of the varying materials and conditions under which commercial forms of stearine pitches are produced, it has been increasingly difficult to obtain such pitches possessing uniform performance from a flame-retarding standpoint. It has also been found exceedingly dicult to manufacture uniform stearine pitchbearing compounds from a physical characteristic standpoint, such as softening point, viscosity and hardness, which have a direct effect on the performance properties of such articles as rubber insulated wire, tubular woven conduits and other articles of commercial significance.

The barium soaps have been found to be particularly effective from a flame retarding standpoint. However, the barium soaps are not readily dispersed in asphalts by simple mixing and uxing together. In an effort to find a method whereby this could be accomplished, it was found that the barium'soaps could rst be mixed with other soaps which were readily dispersed by simple mixing and fluxing, and then in such combination could readily be dispersed in asphalts.

It was found that 50 parts of a barium soap and 50 parts of a zinc soap when mixed together, and then added to an asphalt or a bituminous combination, that iire retarding properties approximating the effectiveness of a manganese soap could be obtained, when added in approximately the same proportions. Percentages required to produce materials of commercial value fall within the range of 4 to 12%. In practice We have found that 6 to 12% is adequate.

Rubber insulated cotton covered 'Wire treated with bituminous materials containing this combination after 6 months exposure have not exhibited the tendency to deteriorate. The degree of deterioration appears to be of about the same magnitude as would be obtained with straight asphai'tic materials.

For example, I have found that when 6% of a mixture of 50% barium laurate and 50% zinc laurate is added to an asphalt having a melting point of ring, and a penetration of 21 aw() grams for 5 seconds, iat e resulting composition has a melting point of F., and a penetration of 20 at 77 F. Viscosity at 300 F. remains the same after the soap addition. These same physical properties can be readily reproduced from batch to batch. Further the flame retarding properties of such a combination are consistent from batch to batch. For example, I have found that when rubber insulated cotton covered Wire is impregnated with this material and an excess is allowed to remain on the wire, and subjected per cent of a combination of parts bar to a 5 inch Bunsen burner fiame While suspended in -a vertical' position, thi occurs to thwar the roa atin of a flame upwargpg A material having a i ing pon of `bituminous mixtures such as a blend of asphalts,

gilsonite, and wax, having melting points varying in range from 200 to 259 F. and penetration values varying from 3 to 15 at 77 F., has a barium and zinc soap combination incorporated therein, is suitable as a finisher for such work, and that the physical properties such as melting point and hardness ls not Substantially changed. Such materials fall well within the `range required of coating materials used in the pr :luotion of hre retarding, rubber insulated cotton covered code Wire and in addition, such compounds have fire retarding properties equal to commercial forms of stearine pitch compounds used in the production of flame retarding, moisture resisting code wire x f-For example, I have found that Jhen eight dm laurate and 50 parts zine laurate are incorporated in an asphalt having a melting point of 238 F., andvekpp tration or at n f.. that the resulting melting point is 231 and the penetration at 77 F., is 9.

I have further found that when rubber insulated cotton wire is saturated with a 140 F. melting point bituminous composition such as described above, and subsequently hnished with a finisher as cited in the above example, that this wire equals in re resistance performance, and in some instances is superior to wire impregnated with commercial forms of stearine pitch saturants and finishers.

The-re are manytypes and sizes of rubber insulated cotton covered wire, and experience has shown that application technique with respect to saturation and finishing must be varied to make all of these various wires behave in a similar manner with respect to fire resistance.

This is true both for the stearine pitch type saturants and finishers as well as the soap types. In brief the proper techm'que required for each type of wire is one whereby the necessary amount of saturant and finisher can be retained in the cotton covering, so that the ash structure formed on burning is adequate to thwart the propagation of a flame. Controllingr factors are the ternperature of the saturating and finishing bath, the speed of the wire through these baths, and the size of the finishing dies. In-certain instances it may even be necessary to double coat the wire, either by having a finishing tank in tandem with the saturating bath which puts on a light smear coat of finisher, or by running the wire through the finishing bath two times.

For some purposes I have found that combinations of several soaps may be used with advantage, particularly to obtain maximum effectiveness with respect to flame retardance. For

example, it has been found that the addition `of '3% iron stearato to an asphalt saturant or 1inisher for the production of code wire and embodying 8% of a barium bine soap combination produces a bituminous composition which possesses very efficient flame retarding characteristics. Other soaps may be included as above described7 such for example, as minor proportions of aluminum soaps, with barium and zinc soap combinations.

This application is a continuation in part of my application, Serial No. 183,160, filed January Biaggi" l .g

' I-Iaving thus described the invention, what is claimed is:

1. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering th'e rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing' coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability lwhen exposed to direct ame of forming a carbonaceous ash film on the surface thereof in sufficient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material selected from the group consis in of thse nat sonit, steam reduced an from petroleum residuaLcoal p pitches, and mixtures thereof which are (maracterized by their nnon-greasy and non-oily appearance and feel, and having incorporated therein at least ondegeatallic soap insoluble injateruand comprising a soap selected rom e soaps of the group of metals consisting Yof'iron,'Ziiifwaluminum, and barium, in an amo nt exceeding fifteen er e weight of the bus composition, saidmmading bituminous composition being fur her carcti'fidby its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

2. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member ,applied to and covering the rubber coating, said textile covering member Vbeing impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash hlm on the surface thereof in suflicient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced. and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of iron, zinc, aluminum, and barium, in an amount not exceeding fifteen per cent by weight of the bituminous composition, said bituminous material having incorporated therein waxes, resins or mixtures thereof in proportions not to exceed 35% of the Weight of the bituminous composition, said name retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures, said bituminous material lconstituting at least 65% of the bituminous base.

3. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash film on thesurface thereof in sufficient amount to form an effective air seal to thereby prevent rapid propagation of ame, said nishing coating comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of iron, zinc, aluminum and barium, in an amount from six to fifteen per cent by weight of the bituminous composition, said flame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

4. As anew article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile: covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash film on the surface thereof in suicient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of manganese, iron, zinc, chromium. cobalt, magnesium, lead and barium, in an amount not exceeding fifteen per cent by weight of the bituminous composition, said dame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

5. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous nishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash film on the surface thereof in sucient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising p a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein a mixture of barium and zinc soaps in an amount not exceeding fifteen per cent by weight of the bituminous composition, said flame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

6. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct :dame of forming a carbonaceous ash film on the surface thereof in sufficient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein a mixture of fifty per cent barium soap and fty per cent Zinc soap in an amount not exceeding fifteen per cent by Weight of the bituminous composition, said iame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

7. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash film on the surface thereof in sufficient amount to form an effective air seal to thereby prevent rapid propagation of flame. said impregnant and said finishing coating each comprising bituminous materials selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their noni 1 murmur greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of iron, zinc, aluminum, and barium, in an amount not exceeding iifteen per cent by Weight of the bituminous composition, said flame retarding bituminouscomposition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

8. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct fia-me of forming a carbonaceous ash film on the surface thereof in suiicient amount to form an eiective air seal to thereby prevent rapid propagation of ame, said impregnant and said finishing coating each comprising bituminous materials selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy rand non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of manganese, iron, zinc, chromium, cobalt, magnesium, lead and barium, in an amount not exceeding fifteen per cent by weight of the bituminous composition, said flame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

9. as a new article of manufacture, a rubber covered insulated wire comprising a Wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member 2- being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over` and covering the textile covering, said bituminous finishing coating being characterized by the ability when exposed to direct flame offorming a carbonaceous asn film on the surface thereof in sufficient amount to form an eiective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material having a melting point between 170 F. and 300 E. and a hardness between 3 and 18 both measured in the manner described and being selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in Water and comprising a soap selected from the soaps of the group of metals consisting of iron, zinc, aluminum, and barium, in an amount not exceeding fifteen per cent by Weight of the bituminous composition, said name retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

10. As a new article of manufacture, a rubber covered insulated Wire comprising a wire having a coating of rubber insulating the same, and a textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a bituminous finishing coating applied over and covering the textile covering, said bituminous iinishing coating being characterized by the ability when exposed to direct flame of forming a carbonaceous ash film on the surface thereof in suiiicient amount to form an effective air seal to thereby prevent rapid propagation of name, said finishing coating comprisin`g a bituminous material having a melting point between 170 F. and 300 F. and a hardness between 3 and 18 and said mpregnant comprising a bituminous material having a melting point of from 100 to 200 F. and a hardness between 15 and 30, both being measured according to the described methods, said bituminous impregnant and said nishing coating each comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in water and comprising a soap selected from the soaps of the group of metals consisting of iron, zinc, aluminum, and barium, in an amount not exceeding fifteen per cent by weight of the bituminous composition, said ame retarding bituminous composition 'being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

11. As a new article of manufacture, a rubber covered insulated wire comprising a wire having a coating of rubber insulating the same, and a Y textile covering member applied to and covering the rubber coating, said textile covering member being impregnated with a bituminous impregnant, and having a 'bituminous nishing coating applied over and covering the textile covering, said bituminous riishing coating being characterized by the ability when exposed to direct name of forming a carbonaceous ash lm on the surface thereof in sufficient amount to form an effective air seal to thereby prevent rapid propagation of flame, said finishing coating comprising a bituminous material having a melting point between 170 F. and 300 F. and a hardness between 3 and 18 both measured iny the manner described and being selected from the group consisting of those natural asphalts, gilsonite, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein at least one metallic soap insoluble in Water and comprising a soap selected from the soaps of the group of metals consisting of manganese, iron, zinc, chromium, cobalt, aluminum, magnesium, lead and barium, in an amount not exceeding ifteen per cent by weight of the bituminous composition, said lame retarding bituminous compo member being impregnated with a bituminous impregnant, and having a name retarding bituminous composition applied over and covering the textile covering, said composition possessing the property when exposed to direct flame of forming on the surface thereof a carbonaceous ash film of suicient density and in suicient amount to form an effective air seal covering the underlying bituminous material to thereby prevent rapid propagation of flame, comprising a bituminous material selected from the group consisting of those natural asphalts, gilsonlte, steam reduced and air blown asphalts from petroleum residua, coal tar pitches, stearine pitches, and mixtures thereof which are characterized by their non-greasy and non-oily appearance and feel, and having incorporated therein a mixture.

of zinc, barium, and aluminum soaps in an amount not exceeding fifteen per cent by weight of the bituminous composition, said ame retarding bituminous composition being further characterized by its ability to maintain substantially predetermined physical characteristics upon cooling after having been subjected to heating to elevated temperatures.

PURDUM M. SNYDER. 

